scholarly journals Borrelia burgdorferi Linear Plasmid 28-3 Confers a Selective Advantage in an Experimental Mouse-Tick Infection Model

2013 ◽  
Vol 81 (8) ◽  
pp. 2986-2996 ◽  
Author(s):  
Daniel P. Dulebohn ◽  
Aaron Bestor ◽  
Patricia A. Rosa
Keyword(s):  
Borrelia Burgdorferi ◽  
Selective Advantage ◽  
Infection Model ◽  
Linear Plasmids ◽  
Content Type ◽  
Tick Infection ◽  
Experimental Mouse ◽  
Segmented Genome ◽  
Infectious Cycle

ABSTRACTBorrelia burgdorferi, the bacterium that causes Lyme disease, has a unique segmented genome consisting of numerous linear and circular plasmids and a linear chromosome. Many of these genetic elements have been found to encode factors critical forB. burgdorferito complete the infectious cycle. However, several plasmids remain poorly characterized, and their roles during infection withB. burgdorferihave not been elucidated. To more fully characterize the role of one of the four 28-kb linear plasmids, lp28-3, we generated strains specifically lacking lp28-3 and assayed the contribution of genes carried by lp28-3 toB. burgdorferiinfection. We found that lp28-3 does not carry any genes that are strictly required for infection of a mouse or tick and that lp28-3-deficient spirochetes are competent at causing a disseminated infection. Interestingly, spirochetes containing lp28-3 were at a selective advantage compared to lp28-3-deficient spirochetes when coinjected into a mouse, and this advantage was reflected in the population of spirochetes acquired by feeding ticks. Our data demonstrate that genes carried by lp28-3, although not essential, contribute to the fitness ofB. burgdorferiduring infection.

scholarly journals Borrelia burgdorferi Linear Plasmid 38 Is Dispensable for Completion of the Mouse-Tick Infectious Cycle

2011 ◽  
Vol 79 (9) ◽  
pp. 3510-3517 ◽  
Author(s):  
Daniel P. Dulebohn ◽  
Aaron Bestor ◽  
Ryan O. M. Rego ◽  
Philip E. Stewart ◽  
Patricia A. Rosa
Keyword(s):  
Borrelia Burgdorferi ◽  
Shuttle Vector ◽  
Linear Plasmid ◽  
Diverse Range ◽  
Antigenic Protein ◽  
Content Type ◽  
Experimental Mouse ◽  
Infectious Cycle

ABSTRACTBorrelia burgdorferi, the causative agent of Lyme disease, exists in a complex enzootic cycle, transiting between its vector,Ixodesticks, and a diverse range of vertebrate hosts.B. burgdorferilinear plasmid 38 (lp38) contains several genes that are differentially regulated in response to conditions mimicking the tick or mouse environments, suggesting that these plasmid-borne genes may encode proteins important for theB. burgdorferiinfectious cycle. Some of these genes encode potential virulence factors, including hypothetical lipoproteins as well as a putative membrane transport system. To characterize the role of lp38 in theB. burgdorferiinfectious cycle, we constructed a shuttle vector to selectively displace lp38 from theB. burgdorferigenome and analyzed the resulting clones to confirm the loss of lp38. We found that,in vitro, clones lacking lp38 were similar to isogenic wild-type bacteria, both in growth rate and in antigenic protein production. We analyzed these strains in an experimental mouse-tick infectious cycle, and our results demonstrate that clones lacking lp38 are fully infectious in a mouse, can efficiently colonize the tick vector, and are readily transmitted to a naive host.

scholarly journals Activity of the Pore-Forming Virulence Factor Listeriolysin O Is Reversibly Inhibited by Naturally Occurring S-Glutathionylation

2017 ◽  
Vol 85 (4) ◽  
Author(s):  
Jonathan L. Portman ◽  
Qiongying Huang ◽  
Michelle L. Reniere ◽  
Anthony T. Iavarone ◽  
Daniel A. Portnoy
Keyword(s):  
Protein Function ◽  
Inhibitory Effect ◽  
Cysteine Residue ◽  
Infection Model ◽  
Listeriolysin O ◽  
Content Type ◽  
Pore Forming Proteins

ABSTRACT Cholesterol-dependent cytolysins (CDCs) represent a family of homologous pore-forming proteins secreted by many Gram-positive bacterial pathogens. CDCs mediate membrane binding partly through a conserved C-terminal undecapeptide, which contains a single cysteine residue. While mutational changes to other residues in the undecapeptide typically have severe effects, mutation of the cysteine residue to alanine has minor effects on overall protein function. Thus, the role of this highly conserved reactive cysteine residue remains largely unknown. We report here that the CDC listeriolysin O (LLO), secreted by the facultative intracellular pathogen Listeria monocytogenes, was posttranslationally modified by S-glutathionylation at this conserved cysteine residue and that either endogenously synthesized or exogenously added glutathione was sufficient to form this modification. When recapitulated with purified protein in vitro, this modification completely ablated the activity of LLO, and this inhibitory effect was fully reversible by treatment with reducing agents. A cysteine-to-alanine mutation in LLO rendered the protein completely resistant to inactivation by S-glutathionylation, and a mutant expressing this mutation retained full hemolytic activity. A mutant strain of L. monocytogenes expressing the cysteine-to-alanine variant of LLO was able to infect and replicate within bone marrow-derived macrophages indistinguishably from the wild type in vitro, yet it was attenuated 4- to 6-fold in a competitive murine infection model in vivo. This study suggests that S-glutathionylation may represent a mechanism by which CDC-family proteins are posttranslationally modified and regulated and help explain an evolutionary pressure to retain the highly conserved undecapeptide cysteine.

scholarly journals CsrA (BB0184) Is Not Involved in Activation of the RpoN-RpoS Regulatory Pathway in Borrelia burgdorferi

2014 ◽  
Vol 82 (4) ◽  
pp. 1511-1522 ◽  
Author(s):  
Zhiming Ouyang ◽  
Jianli Zhou ◽  
Michael V. Norgard
Keyword(s):  
Gene Expression ◽  
Borrelia Burgdorferi ◽  
Animal Studies ◽  
Expression System ◽  
Regulatory Pathway ◽  
Content Type ◽  
Mouse Tissues ◽  
Differential Gene ◽  
Carbon Storage Regulator

ABSTRACTBorrelia burgdorferiencodes a homologue of the bacterial carbon storage regulator A (CsrA). Recently, it was reported that CsrA contributes toB. burgdorferiinfectivity and is required for the activation of the central RpoN-RpoS regulatory pathway. However, many questions concerning the function of CsrA inB. burgdorferigene regulation remain unanswered. In particular, there are conflicting reports concerning the molecular details of how CsrA may modulaterpoSexpression and, thus, how CsrA may influence the RpoN-RpoS pathway inB. burgdorferi. To address these key discrepancies, we examined the role of CsrA in differential gene expression in the Lyme disease spirochete. Upon engineering an induciblecsrAexpression system inB. burgdorferi, controlled hyperexpression of CsrA in a merodiploid strain did not significantly alter the protein and transcript levels ofbosR,rpoS, and RpoS-dependent genes (such asospCanddbpA). In addition, we constructed isogeniccsrAmutants in two widely used infectiousB. burgdorferistrains. When expression ofbosR,rpoS,ospC, anddbpAwas compared between thecsrAmutants and their wild-type counterparts, no detectable differences were observed. Finally, animal studies indicated that thecsrAmutants remained infectious for and virulent in mice. Analyses ofB. burgdorferigene expression in mouse tissues showed comparable levels ofrpoStranscripts by thecsrAmutants and the parental strains. Taken together, these results constitute compelling evidence that CsrA is not involved in activation of the RpoN-RpoS pathway and is dispensable for mammalian infectious processes carried out byB. burgdorferi.

scholarly journals Neutrophils Are Essential for Containment of Vibrio cholerae to the Intestine during the Proinflammatory Phase of Infection

2012 ◽  
Vol 80 (8) ◽  
pp. 2905-2913 ◽  
Author(s):  
Jessica Queen ◽  
Karla J. Fullner Satchell
Keyword(s):  
Immune Response ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Innate Immune ◽  
Infection Model ◽  
Proinflammatory Response ◽  
Necrosis Factor Alpha ◽  
Live Attenuated Vaccine ◽  
Content Type

ABSTRACTCholera is classically considered a noninflammatory diarrheal disease, in comparison to invasive enteric organisms, although there is a low-level proinflammatory response during early infection withVibrio choleraeand a strong proinflammatory reaction to live attenuated vaccine strains. Using an adult mouse intestinal infection model, this study examines the contribution of neutrophils to host defense to infection. Nontoxigenic El Tor O1V. choleraeinfection is characterized by the upregulation of interleukin-6 (IL-6), IL-10, and macrophage inflammatory protein 2 alpha in the intestine, indicating an acute innate immune response. Depletion of neutrophils from mice with anti-Ly6G IA8 monoclonal antibody led to decreased survival of mice. The role of neutrophils in protection of the host is to limit the infection to the intestine and control bacterial spread to extraintestinal organs. In the absence of neutrophils, the infection spread to the spleen and led to increased systemic levels of IL-1β and tumor necrosis factor alpha, suggesting the decreased survival in neutropenic mice is due to systemic shock. Neutrophils were found not to contribute to either clearance of colonizing bacteria or to alter the local immune response. However, when genes for secreted accessory toxins were deleted, the colonizing bacteria were cleared from the intestine, and this clearance is dependent upon neutrophils. Thus, the requirement for accessory toxins in virulence is negated in neutropenic mice, which is consistent with a role of accessory toxins in the evasion of innate immune cells in the intestine. Overall, these data support that neutrophils impact disease progression and suggest that neutrophil effectiveness can be manipulated through the deletion of accessory toxins.

scholarly journals SlyA Is a Transcriptional Regulator Involved in the Virulence of Enterococcus faecalis

2011 ◽  
Vol 79 (7) ◽  
pp. 2638-2645 ◽  
Author(s):  
Charlotte Michaux ◽  
Maurizio Sanguinetti ◽  
Fany Reffuveille ◽  
Yanick Auffray ◽  
Brunella Posteraro ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Galleria Mellonella ◽  
Peritoneal Macrophages ◽  
Bacterial Virulence ◽  
Transcriptional Analysis ◽  
Infection Model ◽  
Wild Type ◽  
Content Type ◽  
Wild Type Parent

ABSTRACTPhylogenetic analysis of the crystal structure of theEnterococcus faecalisSlyA (EF_3002) transcriptional factor places it between the SlyA and MarR regulator subfamilies. Proteins of these families are often involved in the regulation of genes important for bacterial virulence and stress response. To gather evidence for the role of this putative regulator inE. faecalisbiology, we dissected the genetic organization of theslyA-EF_3001 locus and constructed aslyAdeletion mutant as well as complemented strains. Interestingly, compared to the wild-type parent, the ΔslyAmutant is more virulent in an insect infection model (Galleria mellonella), exhibits increased persistence in mouse kidneys and liver, and survives better inside peritoneal macrophages. In order to identify a possible SlyA regulon, global microarray transcriptional analysis was performed. This study revealed that theslyA-EF_3001 locus appears to be autoregulated and that 117 genes were differentially regulated in the ΔslyAmutant. In the mutant strain, 111 were underexpressed and 6 overexpressed, indicating that SlyA functions mainly as an activator of transcription.

scholarly journals Infection of Interleukin 17 Receptor A-Deficient C3H Mice with Borrelia burgdorferi Does Not Affect Their Development of Lyme Arthritis and Carditis

2015 ◽  
Vol 83 (7) ◽  
pp. 2882-2888 ◽  
Author(s):  
Carrie E. Lasky ◽  
Kara E. Jamison ◽  
Darcie R. Sidelinger ◽  
Carmela L. Pratt ◽  
Guoquan Zhang ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Lyme Borreliosis ◽  
Heart Tissue ◽  
Lyme Arthritis ◽  
Mouse Strains ◽  
Interleukin 17 ◽  
Content Type ◽  
C3h Mice ◽  
A Subunit

Recently, a number of studies have reported the presence of interleukin 17 (IL-17) in patients with Lyme disease, and several murine studies have suggested a role for this cytokine in the development of Lyme arthritis. However, the role of IL-17 has not been studied using the experimental Lyme borreliosis model of infection of C3H mice withBorrelia burgdorferi. In the current study, we investigated the role of IL-17 in the development of experimental Lyme borreliosis by infecting C3H mice devoid of the common IL-17 receptor A subunit (IL-17RA) and thus deficient in most IL-17 signaling. Infection of both C3H and C3H IL-17RA−/−mice led to the production of high levels of IL-17 in the serum, low levels in the heart tissue, and no detectable IL-17 in the joint tissue. The development and severity of arthritis and carditis in the C3H IL-17RA−/−mice were similar to what was seen in wild-type C3H mice. In addition, development of antiborrelia antibodies and clearance of spirochetes from tissues were similar for the two mouse strains. These results demonstrate a limited role for IL-17 signaling through IL-17RA in the development of disease following infection of C3H mice withB. burgdorferi.

scholarly journals Analysis of the HD-GYP Domain Cyclic Dimeric GMP Phosphodiesterase Reveals a Role in Motility and the Enzootic Life Cycle of Borrelia burgdorferi

2011 ◽  
Vol 79 (8) ◽  
pp. 3273-3283 ◽  
Author(s):  
Syed Z. Sultan ◽  
Joshua E. Pitzer ◽  
Tristan Boquoi ◽  
Gerry Hobbs ◽  
Michael R. Miller ◽  
...  
Keyword(s):  
Life Cycle ◽  
Borrelia Burgdorferi ◽  
Double Mutant ◽  
Ixodes Scapularis ◽  
Metabolizing Enzymes ◽  
Content Type ◽  
Motility Regulation ◽  
Mutant Cells ◽  
Single Set

ABSTRACTHD-GYP domain cyclic dimeric GMP (c-di-GMP) phosphodiesterases are implicated in motility and virulence in bacteria.Borrelia burgdorferipossesses a single set of c-di-GMP-metabolizing enzymes, including a putative HD-GYP domain protein, BB0374. Recently, we characterized the EAL domain phosphodiesterase PdeA. A mutation inpdeAresulted in cells that were defective in motility and virulence. Here we demonstrate that BB0374/PdeB specifically hydrolyzed c-di-GMP with aKmof 2.9 nM, confirming that it is a functional phosphodiesterase. Furthermore, by measuring phosphodiesterase enzyme activity in extracts from cells containing thepdeA pdeBdouble mutant, we demonstrate that no additional phosphodiesterases are present inB. burgdorferi.pdeBsingle mutant cells exhibit significantly increased flexing, indicating a role for c-di-GMP in motility. Constructing and analyzing apilZpdeBdouble mutant suggests that PilZ likely interacts with chemotaxis signaling. While virulence in needle-inoculated C3H/HeN mice did not appear to be altered significantly inpdeBmutant cells, these cells exhibited a reduced ability to survive inIxodes scapularisticks. Consequently, those ticks were unable to transmit the infection to naïve mice. All of these phenotypes were restored when the mutant was complemented. Identification of this role ofpdeBincreases our understanding of the c-di-GMP signaling network in motility regulation and the life cycle ofB. burgdorferi.

scholarly journals The Borrelia burgdorferi Glycosaminoglycan Binding Protein Bgp in the B31 Strain Is Not Essential for Infectivity despite Facilitating Adherence and Tissue Colonization

2017 ◽  
Vol 86 (2) ◽  
Author(s):  
Samantha Schlachter ◽  
Janakiram Seshu ◽  
Tao Lin ◽  
Steven Norris ◽  
Nikhat Parveen
Keyword(s):  
Lyme Disease ◽  
Borrelia Burgdorferi ◽  
Binding Protein ◽  
Mammalian Host ◽  
Infection Model ◽  
Binding Assays ◽  
Content Type ◽  
Mouse Infection Model ◽  
Successful Infection

ABSTRACTThe Lyme disease-causing organismBorrelia burgdorferiis transmitted into the mammalian host by an infected-tick bite. Successful infection relies on the ability of this extracellular pathogen to persist and colonize different tissues.B. burgdorferiencodes a large number of adhesins that are able to interact with host ligands to facilitate adherence and tissue colonization. Multiple glycosaminoglycan binding proteins present inB. burgdorferioffer a degree of redundancy of function during infection, and this highlights the importance of glycosaminoglycans as host cell receptors for spirochete adherence. Of particular interest in this study isBorreliaglycosaminoglycan binding protein (Bgp), which binds to heparin-related glycosaminoglycans. The properties of abgptransposon mutant and atrans-complemented derivative were compared to those of the wild-typeB. burgdorferiin thein vitrobinding assays and in infection studies using a C3H/HeJ mouse infection model. We determined that the loss of Bgp impairs spirochete adherence, infectivity, and tissue colonization, resulting in a reduction of inflammatory manifestations of Lyme disease. Although Bgp is not essential for infectivity, it is an important virulence factor ofB. burgdorferithat allows adherence and tissue colonization and contributes to disease severity.

scholarly journals The Lon-1 Protease Is Required by Borrelia burgdorferi To Infect the Mammalian Host

2020 ◽  
Vol 88 (6) ◽  
Author(s):  
Christina Thompson ◽  
Charlotte Mason ◽  
Shidoya Parrilla ◽  
Zhiming Ouyang
Keyword(s):  
Borrelia Burgdorferi ◽  
Bacterial Infection ◽  
Bacterial Resistance ◽  
Critical Role ◽  
Mammalian Host ◽  
Infection Model ◽  
Lon Protease ◽  
Content Type ◽  
Growth Defects ◽  
Functional Homolog

ABSTRACT Borrelia burgdorferi encodes a functional homolog of canonical Lon protease termed Lon-2. In addition, B. burgdorferi encodes a second Lon homolog called Lon-1. Recent studies suggest that Lon-1 may function differently from the prototypical Lon protease. However, the function of Lon-1 in B. burgdorferi biology remains virtually unknown. Particularly, the contribution of Lon-1 to B. burgdorferi fitness and infection remains hitherto unexplored. Herein, we show that Lon-1 plays a critical role for the infection of B. burgdorferi in a mammalian host. We found that lon-1 was highly expressed during animal infection, implying an important function of this protein in bacterial infection. We further generated a lon-1 deletion mutant and an isogenic complemented strain. Relative to that of the wild-type strain, the infectivity of the mutant was severely attenuated in a murine infection model. Our data also showed that the mutant displayed growth defects in regular BSK-II medium. Furthermore, bacterial resistance to osmotic stress was markedly reduced when lon-1 was inactivated. When exposed to tert-butyl hydroperoxide, survival of the lon-1 mutant was impaired. In addition, production of several virulence factors, such as BosR, RpoS, and OspC, was elevated in the mutant. These phenotypes were restored when the lon-1 mutation was complemented. Finally, we created a lon-1(S714A) mutant and found that this mutant failed to infect mice, suggesting that the proteolytic activity of Lon-1 is essential for bacterial infection. Taken together, these results demonstrate that Lon-1 is required by B. burgdorferi to infect animal hosts and to cope with environmental stresses.

scholarly journals Novel Role for theyceGHTellurite Resistance Genes in the Pathogenesis of Bacillus anthracis

2013 ◽  
Vol 82 (3) ◽  
pp. 1132-1140 ◽  
Author(s):  
Sarah E. Franks ◽  
Celia Ebrahimi ◽  
Andrew Hollands ◽  
Cheryl Y. Okumura ◽  
Raffi V. Aroian ◽  
...  
Keyword(s):  
Bacillus Anthracis ◽  
Resistance Genes ◽  
Immune Defense ◽  
Infection Model ◽  
Oxygen Species ◽  
Host Defenses ◽  
Content Type ◽  
Human Whole Blood ◽  
Transposon Mutants

ABSTRACTBacillus anthracis, the causative agent of anthrax, relies on multiple virulence factors to subvert the host immune defense. UsingCaenorhabditis elegansas an infection model, we screened approximately 5,000 transposon mutants ofB. anthracisSterne for decreased virulence. One of the attenuated mutants resulted in loss of expression ofyceGandyceH, the last two genes in a six-gene cluster of tellurite resistance genes. We generated an analogous insertional mutant to confirm the phenotype and characterize the role ofyceGHin resistance to host defenses. Loss ofyceGHrendered the mutants more sensitive to tellurite toxicity as well as to host defenses such as reactive oxygen species and the cathelicidin family of antimicrobial peptides. Additionally, we see decreased survival in mammalian models of infection, including human whole blood and in mice. We identify a novel role for theyceGHgenes inB. anthracisSterne virulence and suggest thatC. elegans is a useful infection model to study anthrax pathogenesis.

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